Depot Antipsychotics

February 2002

Psychotic disorders are usually lifelong—so treatment must continue over many years. Unfortunately, poor compliance is an obstacle to stability for many people with schizophrenia and other chronic mental illnesses.Developed in the 1960s, long-acting antipsychotic drugs, administered intramuscularly every 1 to 6 weeks, represent an assured-delivery system. They also circumvent such pharmacokinetic hurdles as absorption and hepatic biotransformation. A survey in the United Kingdom found that among 390 outpatients with psychotic disorders, approximately 29% were prescribed depot antipsychotics.1 Use in the United States is probably lower.To evaluate the safety and efficacy of long-acting depot antipsychotic preparations, Adams and coauthors conducted a literature search.2 Studies reviewed compared depot antipsychotics with placebo, an oral agent, or another depot agent for people with schizophrenia or related conditions.Dr Adams's group reached several conclusions. Compared to placebo, fluphenazine (Prolixin) decanoate reduces the apparent rate of relapse between 12 weeks and 2 years from 49% to 21%. On the adverse side, for every two to seven people who receive a depot, one will suffer a significant movement disorder.In some studies, depot preparations appeared superior to oral antipsychotics. However, in reviews with over 800 subjects, there was no statistical advantage for depots in prevention of relapse. Patients participating in these trials tend to be more compliant with oral medication than patients not participating in a research study, which would reduce the benefit of the depots.No depot antipsychotic seemed superior to any other, and high depot doses showed no added benefit for treatment-resistant cases. "Ultralow" doses, however, offered little more than placebo.An independent study reviewed satisfaction with and attitude towards depot antipsychotics.3 In general, patients currently taking depot injections found them more convenient than daily tablets.Depot antipsychotics are useful for patients who prefer the convenience of this approach or cannot comply on a regular basis. In addition to being used to treat patients with schizophrenia and related disorders, depot antipsychotics might be considered for those with severe mood disorders or dementia. As the study by Adams et al points out, long-term movement disorders are an unwanted consequence of typical antipsychotics.2 A long-acting injectable preparation of risperidone (Risperdal) awaits approval in the United States, and similar preparations of other atypical antipsychotics are being studied.1Foster K, Meltzer H, Gill B, et al: Adults with a psychotic disorder living in the community. OPCS Surveys of Psychiatric Morbidity in Great Britain, Report 8. London: HMSO; 1996.2Adams CE, Fenton MKP, Quraishi S, David AS: Systematic meta-review of depot antipsychotic drugs for people with schizophrenia. Br J Psychiatry 2001;179:290-299.3Walburn J, Gray R, Gournay K, Quraishi S, David AS: Systematic review of patient and nurse attitudes to depot antipsychotic medication. Br J Psychiatry 2001;179:300-307.